Band 399, Heft 4

Neurological diseases like Alzheimer’s disease, epilepsy, parkinsonism, depression, Huntington’s disease and amyotrophic lateral sclerosis prevailing globally are considered to be deeply influenced by oxidative stress-based changes in the biochemical settings of the organs. The excess oxygen concentration triggers the production of reactive oxygen species, and even the intrinsic antioxidant enzyme system, i.e. SOD, CAT and GSHPx, fails to manage their levels and keep them under desirable limits. This consequently leads to oxidation of protein, lipids and nucleic acids in the brain resulting in apoptosis, proteopathy, proteasomes and mitochondrion dysfunction, glial cell activation as well as neuroinflammation. The present exploration deals with the evidence-based mechanism of oxidative stress towards development of key neurological diseases along with the involved biomechanistics and biomaterials.

Metformin is a widely used antidiabetic drug, and there is evidence among diabetic patients that metformin is a chemopreventive agent against multiple cancers. There is also evidence in human studies that metformin is a cancer chemotherapeutic agent, and several clinical trials that use metformin alone or in combination with other drugs are ongoing. In vivo and in vitro cancer cell culture studies demonstrate that metformin induces both AMPK-dependent and AMPK-independent genes/pathways that result in inhibition of cancer cell growth and migration and induction of apoptosis. The effects of metformin in cancer cells resemble the patterns observed after treatment with drugs that downregulate specificity protein 1 (Sp1), Sp3 and Sp4 or by knockdown of Sp1, Sp3 and Sp4 by RNA interference. Studies in pancreatic cancer cells clearly demonstrate that metformin decreases expression of Sp1, Sp3, Sp4 and pro-oncogenic Sp-regulated genes, demonstrating that one of the underlying mechanisms of action of metformin as an anticancer agent involves targeting of Sp transcription factors. These observations are consistent with metformin-mediated effects on genes/pathways in many other tumor types.

The human genome encodes two highly similar cytosolic Hsp90 proteins called isoforms Hsp90α and Hsp90β. Of the 300 client proteins for Hsp90 identified so far only a handful interact specifically with one Hsp90 isoform. Here we report for the first time that Hsp90 cochaperone p23 binds preferentially to Hsp90α and that this interaction is mediated by the middle domain of Hsp90α. Based on the homology modeling, we infer that the middle domains in the Hsp90α dimer bind stronger with each other than in the Hsp90β dimer. Therefore, compared to Hsp90β, Hsp90α may adopt closed conformation more easily. Hsp90 interacts with p23 in the closed conformation. Hsp90α binds human recombinant p23 about three times stronger than Hsp90β but with significantly smaller exothermic enthalpy as determined by isothermal titration calorimetry of direct binding between the purified proteins. As p23 binds to Hsp90 in a closed conformation, stabilization of the Hsp90α dimer in the closed conformation by its middle domains explains preference of p23 to this Hsp90 isoform.

We show here for the first time that HSA possesses two nucleic acid-(NA) binding sites and we estimated the relative contributions of the nucleotide links of (pN) n to their total affinity for these binding sites with higher and lower affinity for NAs. The minimal ligands of these binding sites are ortho phosphate ( K d =3.0 and 20.0 m m ), various dNMPs (5.6–400 μ m and 0.063–18 m m ) and different rNMPs (4.9–30 μ m and 14–250 μ m ). Maximal contribution to the total affinity of all NAs to the first and second sites was observed for one nucleotide and was remarkably lower for three additional nucleotide units of (pN) n (n=1–4) with a significant decrease in the contribution at n=5–6, and at n≥7–8 all dependencies reached plateaus. For d(pA) n and r(pA) n a relatively gradual decrease in the contribution to the affinity at n=1–6 was observed, while several d(pN) n , demonstrated a sharp increase in the contribution at n=2–4. Finally, all (pN) n > 10 demonstrated high affinity for the first (1.4–150 n m ) and the second (80–2400 n m ) sites of HSA. Double-stranded NAs showed significantly lower affinity comparing with single-stranded ligands. The thermodynamic parameters characterizing the specific contribution of every nucleotide link of all (pN) 1−9 (ΔG°) to their total affinity for HSA were estimated.

Human phospholipid scramblase 3 (hPLSCR3) is a single pass transmembrane protein that plays a vital role in fat metabolism, mitochondrial function, structure, maintenance and apoptosis. The mechanism of action of scramblases remains still unknown, and the role of scramblases in phospholipid translocation is heavily debated. hPLSCR3 is the only member of scramblase family localized to mitochondria and is involved in cardiolipin translocation at the mitochondrial membrane. Direct biochemical evidence of phospholipid translocation by hPLSCR3 is yet to be reported. Functional assay in synthetic proteoliposomes upon Ca 2+ and Mg 2+ revealed that, apart from cardiolipin, recombinant hPLSCR3 translocates aminophospholipids such as NBD-PE and NBD-PS but not neutral phospholipids. Point mutation in hPLSCR3 (F258V) resulted in decreased Ca 2+ binding affinity. Functional assay with F258V-hPLSCR3 led to ~50% loss in scramblase activity in the presence of Ca 2+ and Mg 2+ . Metal ion-induced conformational changes were monitored by intrinsic tryptophan fluorescence, circular dichroism, surface hydrophobicity changes and aggregation studies. Our results revealed that Ca 2+ and Mg 2+ bind to hPLSCR3 and trigger conformational changes mediated by aggregation. In summary, we suggest that the metal ion-induced conformational change and the aggregation of the protein are essential for the phospholipid translocation by hPLSCR3.

This study aimed to investigate the mechanism of lncRNA-KCNQ1OT1 on macrophage polarization to ameliorate particle-induced osteolysis. We used polymethylmethacrylate (PMMA) to induce primary bone marrow-derived macrophages (BMMs) obtained from mice and the RAW264.7 cell line, and found that the tumor necrosis factor-alpha (TNF-α) concentration and inducible nitric oxide synthase (iNOS) expression was increased, while interleukin (IL)-10 concentration and Arg1 expression were decreased in PMMA-induced cells. KCNQ1OT1 and IL-10 expression were both suppressed and miR-21a-5p expression was promoted in PMMA-induced cells. Overexpression of KCNQ1OT1 reversed the effect of PMMA on RAW264.7 cells, such as the reduced TNF-α concentration and iNOS expression, and increased IL-10 concentration and Arg1 expression in PMMA-induced cell transfected with pcDNA-KCNQ1OT1. The luciferase assay confirmed that IL-10 is a target of miR-21a-5p. RNA immunoprecipitation (RIP) and RNA pull-down experiments demonstrated that KCNQ1OT1 functions as a miR-21a-5p decoy. Thus, lncRNA KCNQ1OT1 induces M2 macrophage polarization to ameliorate particle-induced osteolysis by inhibiting miR-21a-5p.

We investigated thoroughly the effect of lncRNA PART1 on prostate cancer cells proliferation and apoptosis, through regulating toll-like receptor (TLR) pathways. LncRNA PART1 expression was also examined by quantitative real-time polymerase chain reactions (qRT-PCR) in human tissues and the cells lines LNCaP and PC3. After transfection with si-PART1 or control constructs, the cell viability was measured by MTS and colony formation assays. In addition, the apoptosis rate of the prostate cancer cells was validated by TUNEL staining. Relationships between lncRNA PART1 expression and TLR pathway genes were demonstrated by qRT-PCR and Western blotting. High levels of lncRNA PART1 expression were correlated with advanced cancer stage and predication of poor survival. LncRNA PART1 levels was increased in PCa cells treated with 5α-dihydrotestosterone (DHT), confirming PART1 was directly induced by androgen. Moreover, down-regulation of lncRNA PART1 inhibited prostate cancer cell proliferation and accelerated cell apoptosis. In addition, lncRNA PART1 induced downstream genes expression in TLR pathways including TLR3 , TNFSF10 and CXCL13 to further influence prostate cancer cells, indicating its carcinogenesis on prostate cancer. LncRNA PART1 promoted cell proliferation ability and apoptosis via the inhibition of TLR pathways in prostate cancer. LncRNA PART1 could hence be considered as a new target in the treatment of prostate cancer.

This study was aimed to investigate the potential regulatory mechanism of high-content hydrogen water (HHW) in non-alcoholic fatty liver disease (NAFLD). A high-fat diet (HFD)-induced NAFLD mice model and cellular model were prepared. The serum levels of alanine transaminase (ALT), aspartate transaminase (AST), total cholesterol (TCH) and triglycerides (TG) were measured. The expression levels of representative five microRNA (miRNAs) (miR-103, miR-488, miR-136, miR-505 and miR-148a) in liver tissues were determined by quantitative real-time PCR (qRT-PCR). The target of miR-136 was validated by RNA immunoprecipitation (RIP) and pull-down assay. MiR-136, MEG3 and nuclear factor erythroid 2-related factor 2 (Nrf2) expression levels following cell treatment were detected in hepatocytes using qRT-PCR and Western blotting. Moreover, cell viability and TG content were conducted. MiR-136 was downregulated, MEG3 as well as Nrf2 was upregulated and serum lipid level was reduced in NAFLD mice model after HHW treatment, which exerted the same effect in cellular model. RIP and RNA pull-down assay confirmed that MEG2 was a downstream target of miR-136. What’s more, HHW ameliorated lipid accumulation by regulating miR-136/MEG3/Nrf2 axis in vitro and in vivo . Hence, HHW alleviated NAFLD by downregulation of miR-136 through mediating Nrf2 via targeting MEG3.